McCuaig said the timeline depends in part on any impact from elections held June 12, in which the Liberal Party won majority representation in Ontario province.

Faster than a speeding locomotive? Not quite. But the Ontario government's promise to electrify all GO lines within a decade presents a serious challenge.

"We know it's a really aggressive timeframe. But, hey, we're looking forward to the opportunity to see how much we can actually deliver," the CEO told local media.

System electrification would help increase capacity and service frequency, offer more reverse-peak and off-peak service, and benefit the environment, McCuaig said. As well, additional stops in and near Toronto could aid passenger flows constrained by current limitations in Toronto Transit Commission (TTC) urban rail offerings.

Ontario rail advocates had hoped the Union Pearson Express, linking Toronto Union Station with Lester B. Pearson International Airport, would be electrified from the start. Metrolinx opted for a diesel service startup, to take place next year, using 18 Tier-4 diesel multiple-units (DMUs) supplied by Sumitomo,.with conversion to electrification in the future.